President-elect Joe Biden says Americans won't be forced to take a coronavirus vaccine when one becomes available in the US.
It comes as the nation's health protection agency for the first time urged "universal mask use" indoors, apart from when Americans are at home.
The Centers for Disease Control (CDC) said the US had "entered a phase of high-level transmission" of the virus.
On Friday the US recorded over 2,500 deaths and nearly 225,000 new cases.
It has confirmed 14.3 million cases and more than 278,000 deaths.
Mr Biden - who is due to take office on 20 January - also said he expected his inauguration to be a scaled-back event without large crowds because of coronavirus concerns.
"My guess is there'll still be a platform ceremony but I don't know how it's all going to work out," he said.
What is Biden's policy on vaccines?
Pfizer, which says its vaccine has been shown to be 95% effective in clinical trials, and Moderna, which says its jab is 94% effective, have both applied to the Food and Drug Administration to distribute their drugs in the US.
The UK on Wednesday became the first country in the world to approve the Pfizer vaccine.
Earlier on Friday Vice-President Mike Pence said during a visit to Atlanta's CDC that federal approval for a Covid-19 vaccine could be "a week-and-a-half away."
Speaking in Wilmington, Delaware, the US president-elect said it would not be necessary to make a coronavirus vaccine mandatory.
"I will do everything in my power as president to encourage people to do the right thing and when they do it, demonstrate that it matters," he said.
The Pew Research Center says just 60% of Americans are currently prepared to take a coronavirus vaccine, up from 51% who said the same in September.
On Thursday Mr Biden told CNN he would be happy to take a vaccine in public to allay potential concerns about its safety. Three former presidents - Barack Obama, George W Bush and Bill Clinton - have said they are also prepared to be inoculated publicly.
Mr Biden has also reiterated his call for Americans to wear a mask for 100 days - a measure that he said combined with vaccine distribution would see deaths "drop off the edge".
"My hope is they will then be inclined to say it's worth the patriotic duty to go ahead and protect other people," Mr Biden said.
Fear of political wrangling
The US fight to control the coronavirus pandemic is about to slam head-first into a national anti-vaccine movement that is stubbornly pervasive.
That reality may be behind President-elect Biden's statement that he would not support a government mandate that all Americans receive a Covid-19 vaccination. The attempt to implement one - even if supported by science and legal precedent dating back more than a century - could create a groundswell of opposition that would prove counterproductive to public health.
Such was the case with mask-wearing - a less intrusive step to prevent the spread of the virus - which, over the past six months, has become infused with politics.
Mr Biden, and state governors who would be on the front lines of any such mandate, might prefer to target only certain segments of the population more at risk of contracting or spreading Covid-19. For instance, employers could be encouraged to require healthcare and nursing home workers to be immunised, and most children already must have up-to-date shot records before attending public or private schools.
While the speedy development of multiple vaccines has offered reason for hope of more normal life after the coronavirus pandemic, a brewing vaccination fight is just one example of how managing this public-health crisis in the coming months will not be an easy task for the Biden administration.
What is the CDC advising Americans to do?
The health body said it was now recommending that people wear masks anywhere outside their own homes - including indoors.
It said the country was in a phase of "high-level transmission" as colder weather was seeing more people spend more time indoors.
About half of new cases were the result of transmission from infected people who did not have any symptoms, the CDC said.
It said mask wearing, physical distancing and avoiding non-essential indoor spaces and crowded outdoor spaces were part of a "multi-pronged" approach needed to "provide a bridge" to a future where vaccines were widely available and normal life could resume.
On Thursday Mr Biden said he would make mask-wearing in federal buildings mandatory.
Meanwhile, California Democratic Governor Gavin Newsom has issued a stay-at-home order for much of his state. On Wednesday, Los Angeles Mayor Eric Garcetti issued an order restricting all public travel on foot or vehicle, adding: "It's time to cancel everything."
What about US jobs?
Mr Biden described the latest jobs data as "grim".
Figures from November, released earlier on Friday, showed that a lower-than-expected 245,000 new jobs were added as the rate of new daily infections almost doubled.
"It shows an economy that's stalling and remains in the midst of one of the worst economic and job crisis in modern history," Mr Biden said.
He predicted "the future will be very bleak" if lawmakers fail to pass a coronavirus rescue aid package immediately.
Unless Congress enacts another relief bill, more than nine million jobless Americans will be cut off from unemployment benefits after Christmas.
Lawmakers from both parties have been inching towards a $900bn (£670bn) plan that would include expanded unemployment benefits.